1. Field of the Invention
The present invention relates to an internal combustion engine. In particular, the present invention relates to an exhaust gas recirculation (“EGR”) system and method to operate the system using paired cylinders.
2. Background
In various engines, exhaust gases may be generated as combustion chambers or cylinders perform their firing strokes. Exhaust gas recirculation (“EGR”) is a widely used method to utilize these exhaust gases to improve combustion efficiency. In general, EGR improves fuel consumption and reduces emission of nitrogen oxides (“NOx”) by recirculating exhaust gases through engine cylinders as they intake fuel and air.
Modern EGR systems may utilize high pressure routing, in which exhaust gas is redirected into a combustion chamber or cylinder from other cylinders, or low pressure routing, in which exhaust gas is redirected into cylinders after going through a catalytic converter. In both of these systems, exhaust gases are ultimately exhausted from the engine through an exhaust pathway. These gases may be redirected along many points in their exhaust pathways back to the cylinders to perform EGR. There still exists a need for improved EGR systems and methods to operate these systems.